DESCRIPTION (provided by investigator): Project summary/abstract From 2002 to 2008 NIAID supported a trial of pneumococcal vaccination in Fijian infants. Children in Fiji are known to be at high risk of pneumococcal disease, especially pneumonia and meningitis. Two types of vaccine are available for use in children to prevent pneumococcal disease. The new pneumococcal conjugate vaccine has been shown to be effective in young children in the USA and elsewhere, but there are two main barriers to its use in the developing world. The number of pneumococcal types covered by the vaccine is inadequate for developing countries, where there is a wider range of types than in the US. In addition, the price of the vaccine is too high, especially for lower middle income countries like Fiji that are not eligible for support from the Global Alliance for Vaccines and Immunization (GAVI). The pneumococcal trial in Fiji evaluated regimens of pneumococcal vaccination that employed reduced numbers of pneumococcal conjugate vaccine and used pneumococcal polysaccharide vaccine given at 12 months of age as a booster. The immunity of children in the trial was then evaluated by examining their antibody response to a small dose of pneumococcal polysaccharide at 17 months. The trial showed that a regimen using only two doses of conjugate vaccine appeared to be effective, and was well boosted by the polysaccharide vaccine at 12 months. However, those children who received the polysaccharide vaccine as a booster at 12 months of age responded poorly to the 17 months challenge dose, by comparison to those children who did not receive the polysaccharide vaccine at 12 months. To see whether this has produced any lasting negative effect on these children's immunity, and to see if the children are at increased risk of either carriage of pneumococci or pneumococcal disease we propose a study with three components: To investigate, among children who did or did not receive pneumococcal polysaccharide vaccine (PPS) at 12 months of age: 1. the long-term safety of PPS by expanding the adverse events surveillance 2. the risk of pneumococcal carriage 3. the numbers of B lymphocytes recognizing pneumococcal antigens Relevance This study is designed to evaluate the immunological safety of pneumococcal polysaccharide vaccine when given to children at 12 months of age. If there is a risk associated with the use of this vaccine, special measures will need to be taken to ensure the safety of the Fijian children involved in the first Fiji pneumococcal vaccine trial. If this is the case, countries that are either using or considering this strategy will need to reconsider their current policies. PUBLIC HEALTH RELEVANCE: Project Narrative This study is designed to evaluate the immunological safety of pneumococcal polysaccharide vaccine when given to children at 12 months of age. If there is a risk associated with the use of this vaccine, special measures will need to be taken to ensure the safety of the Fijian children involved in the first Fiji pneumococcal vaccine trial. If this is the case, countries that are either using or considering this strategy will need to reconsider their current policies.